1. Field of the Invention
The invention relates to a mailing machine of the type having a controller, a security module, and a non-removable program memory. The invention further pertains to a method of intializing a mailing machine of this type. The term mailing machine, as used herein, is to be understood as including, for example, franking machines and postage-calculating scales, i.e. mail scales, with an integrated postage calculator and similar mailing devices for which approval from the postal authorities is required.
Franking machines have been known since the 1920s and even today are constantly being further refined. Their principle is based on the idea that monetary data are managed in the franking machine. In each franking operation, the current residual amount is reduced in the descending register by the franking amount printed onto the item to be dispatched. When the residual amount has been used up, the franking machine can be recharged with a prescribed amount of credit. The residual amount is thereby incremented by the amount of the credit. For protection against manipulation, for example of the residual amount in the descending register, the franking machines are equipped with a security housing.
More recent franking machines produced and distributed by the assignee, Francotyp-Postalia AG & Co. of Germany, use digitally operating printing modules, such as for example, for the first time in the world, inkjet printers in the franking machines of the JetMail® type or thermal-transfer printers in the franking machines of the T1000 type. It is consequently possible in principle to print other information onto a filled letter in the region of the franking stamp or to carry out printing differently in any way desired.
Commonly assigned U.S. Pat. No. 5,805,711 (European patent EP 0 660 269 B1), entitled “Method of Improving the Security of Postage Meter Machines” describes a franking machine which has a closable and sealed flap, which allows access to the hardware behind (EPROM socket) only to a restricted group of especially trustworthy persons. It could be assumed here that no manipulation of the franking machine would be carried out by these persons. The closable and sealed flap is also referred to as the postal authority flap, which can be opened only by postal authority officials, for example to recharge a credit at the post office. Another solution proffered by the assignee is based on a flap which is appropriately designed for the “Master-PROM” method. In this method, a service technician changes the printing-block or postage-table ROM for a special ROM—the MASTER-PROM—which, after starting the JetMail, authorizes the technician to access regions of the machine which in some cases are highly sensitive. For example, this allows monetary amounts to be manipulated.
In the case of franking machines which are equipped with a digital printer, a promotional printing block can easily be changed. However, the number of promotional printing blocks is restricted by the storage capacity of the EPROM. The service technician should therefore have access at least to the printing-block EPROM socket, in order to be able to change the printing-block EPROM independently. Consequently, a solution was sought for a franking machine which, with the postal authority flap partly open, can nevertheless guarantee security. Commonly assigned European patent application EP 762 338 A2 proposes the formation of a MAC check sum in respect of the data content of an EPROM for checking the integrity of the data and the program code of printing-block EPROMs which are inserted into the externally accessible socket in the case of a franking machine with the postal authority flap open. The exchanging of the modules is relatively easy if the ROM modules are, for example, in DIL sockets. If in the future, in the course of component miniaturization, different forms of housing package are chosen, a connection via sockets will no longer be possible, i.e. the exchange of ROM modules will be made impossible for the service technician.